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Conventional systems VS. Rainplus system

There are two types of rainwater drainage systems:
conventional systems that are incorrectly called
gravity systems, and the Rainplus® siphonic system,
which is also known as a vacuum system or full
section system.

Both use the force of gravity but in a decidedly
different manner, resulting in differences in
performance, design and calculation.

conventional drainage system

A conventional drainage system can be designed
for large surface areas but does not cut off air flow
into the pipe. For this reason pipes are sized for filling
ratios of 20% or 33% (depending on national or local
standards and regulations) allowing considerable
amounts of air into the pipes of 80% or 67% of the
pipe section.

In conventional roof drainage, the outlets are
simple “funnels” installed on the roof covering and
connected to the downpipes which are as high as
the building and the water collectors which require
a gradient of at least 1%, are dimensioned for a
maximum filling factor of 70%.

When the water collectors are very long and it is not
possible to provide the minimum slope necessary
due to the limited space available, the only solution is
to increase the size of the pipes with a consequent
rise in installation costs.

Rainplus® siphonic drainage system

The Rainplus® siphonic drainage system is made
up of special outlets that incorporate an anti-vortex
plate that prevents air entering into the pipes. The
outlets are connected via short pipes of relatively
small diameters to the horizontal water collector
which is located just under the building roof.

The collector pipe, generally installed at the highest
possible position, runs horizontally (no fall angle
is required) untill it reaches connection with the
downpipe. The downpipe drops into the drainage
line which is buried in the ground and conveys the
water straight into a collection tank or the municipal
stormwater mains.

The absence of air in the system allows it to run
100% full of water making use of the entire pipe
section and vastly increasing flows that are 10 times
faster when compared to conventional drainage
systems.

Flow in a conventional outlet

In conventional roof drainage systems,
the outlet does not incorporate any sort of insert
or device, hence the flow entering the system is
characterized by a vortex that pulls air into the
pipes.

Flow in a Rainplus® outlet

With the Rainplus® siphonic drainage system,
at design flow values, the roof outlets prevent air
from entering and forming a vortex thus ensuring
the system works at full capacity; in such
conditions design can be based on the equations
of fully developed flow rates operating at positive
or negative pressures (Bernoulli’s energy
conservation principle).

Support

Valsir provides complete support both during the planning phase and on site, thanks to a first-class technical office made up of a team of highly experienced engineers, capable of dealing with the most complex system requirements.

Silvestro Software

Silvestro is a software program created by Valsir to help planners in the creation of water supply and waste systems. Thanks to its ease of use it allows the Valsir products to be easily adopted in any project.